EP0713811B1 - Brake installation with a hydrodynamic retarder, particularly for motor vehicles - Google Patents

Description

The invention relates to a brake system with a hydrodynamic Retarders, in particular for motor vehicles. The preamble of claim 1 is referenced.

Brake systems of this type come in a large number of variants became known, see e.g. DE 44 08 350 A (document 1). Also knows to see retarders from a large number of publications for example DE 29 27 582 (document 2). Finally are Control devices for controlling the degree of filling of the work space from Retarders have become known, see for example DE 30 28 429 (publication 3).

Current brake systems have a control device that a Proportional valve includes, further a sump line between the proportional valve and working fluid sump. The swamp is also with the work space of the Retarders connected via a riser. When braking, by means of of the proportional valve via the sump line pressure on the mirror of the Applied sump applied. This then increases in Rise channel and arrives in the work space, which they work with or less stuffed. The proportional valve mentioned is also connected to one Air separator (oil compartment) connected, which the working fluid - in general oil - separates from the trapped air and back into recirculates the circuit while the air is discharged to the outside.

The working fluid consisting of oil is also used to lubricate the Retarder's bearings used.

A heat exchanger is assigned to the braking system in order to reduce the considerable dissipate heat generated during braking.

In the operation of braking systems of the kind described an unsolved problem has surfaced at high speeds (> 2000 min ^-1): Over time, disappeared more and more oil from the entire brake system. In addition, it was found that the bearing temperatures rose significantly at these high speeds without load.

There are a variety of ways to exit Case drain - see e.g. Publication (3).

From the multitude of possibilities, the inventors have the real cause of how recognized as follows: It has long been known that in brake-free operation, i.e. in the oil-free working area of the retarder, the air trapped there circulates and thus generates an undesirable power loss. It was all possible efforts are made to make this undesirable To prevent air circulation - see publication (2). But not what recognized, and what the inventors found out for the first time is the fact that the air not only circulates in the work area but also a pressure builds up, and that this pressure acts on the oil sump. The Action takes place via the above-mentioned riser, the one with the swamp in whose bottom area is in conductive connection. The pressure works from below on the oil mass of the swamp. This will pass oil through the the so-called sump line is pressed, gets to the proportional valve, from there in the air separator mentioned, the so-called oil subspace. In case of an attack the air separator is capable of correspondingly large amounts of oil at this point its function no longer to be performed, so that oil through the ventilation duct is discharged in impermissibly large quantities and gets outdoors.

Accordingly, the teaching of the invention is to provide means to when not braking, a pressure balance on the mirror of the To achieve working fluid sump acting forces. So it will avoided that the unwanted airflow generated when not braking escapes oil from the system.

The invention is explained in more detail with reference to the drawing.

Figure 1 illustrates a brake system according to the invention Idle mode, while Figure 2 shows the system in braking mode.

The following can be seen in detail from both figures:

The retarder 1 has a rotor R and a stator S. The Retarder housing 2 forms a main room 2.1, in which there is an oil sump is located, also an adjoining room 2.4. A partition 2.2 separates the Main room 2.1 from a riser 2.3.

The brake system has a control device. This includes as essential part a proportional valve 3, with integrated 3/2-valve. A Line 3.1 provides a connection between the main room 2.1 and the Proportional valve 3 ago. A line 3.2 leads to an oil room 3.3. This serves as an oil separator. It is connected to a ventilation duct 3.4 connected with a 3.5 in. leakage oil return line from the bearings Connection is established.

As you can see, riser duct 2.3 is located in the working area of retarder 1 conductive connection, namely via its stator S.

A heat exchanger 4 is provided. This is on a line 4.1 the work area of the retarder 1 connected and connected via a line 4.2 the riser 2.3. Heat exchanger 4 also has an inlet 4.3 and a process 4.4 for cooling water.

The following are very important components of the invention: Retarders 1 has a gap 1.1 between rotor R and stator S. Between this Gap 1.1 and the main room 2.1 can be made a conductive connection or be prevented. You can see in the connected to gap 1.1 Channel a throttle 1.2, further - as an extremely important element - a 2/2 valve 1.3. Valve 1.3 can be connected to main room 2.1 via an outlet 1.4 and via a line 1.5 to the 3/2 way valve.

Valve 1.3 remains in brake-free operation - hereinafter referred to as "gap shut-off valve" called - opened. In the specific case, it is 1.6 by its spring kept open. There is no increase in oil in the sump 3.1. The Oil levels in the main room 2.1, in the side room 2.4 and in the riser 2.3 are all the same height. The one generated in the working area of the retarder 1 Air flow is discharged via the sump line 3.1.

A particularly favorable side effect is as follows: the work area of the retarder sucks in the oil-air mixture via the riser 2.3. It forms an oil-air mixture in the circuit and even in the riser itself. Due to the centrifugal force, a certain amount of oil differs in the Working area of the retarder 1. This leads to a reduction in both Power loss as well as for cooling.

In braking operation, as can be seen from Figure 2, acts via the sump 3.1, of Proportional valve 3 outgoing, air pressure on the level of the sump in the Main room 2.1. This will transfer oil from the main room 2.1 to the riser 2.3 pressed, flowing around the lower edge of the partition 2.2. oil rises in the rising duct 2.3, through the wall of the stator S Retarder 1, and fills the working space of the retarder.

Line 1.5 is also pressurized by the 3/2 way valve 3, so that the gap shut-off valve 1.3 closes. Thus, the conductive connection between the working room of the retarder 1 and the main room 2.1 cordoned off. On the arrows, the pressure directions or flow direction suggest, is referred.

• Es wird zuverlässig vermieden, daß im bremsfreien Betrieb der Ölsumpf durch die Sumpfleitung entleert wird, und es wird daher eine unzulässige Leckage unterbunden.
• Die Ölversorgung der Lager bleibt sichergestellt.
• In der Steigleitung bildet sich ein Öl-Luft-Gemisch, das in den Arbeitsraum des Retarders gelangt, dort einen Ölfilm an den Innenwänden des Arbeitsraumes bildet, was zu einer Verringerung der Verlustleistung und zu einer Kühlung des Retarders führt. Die erzeugte Wärme aus der Verlustleistung wird hierbei über den Wärmetauscher abgeführt.

The invention achieves the following in detail:

• It is reliably avoided that the oil sump is emptied through the sump line during brake-free operation, and an inadmissible leakage is therefore prevented.
• The oil supply to the bearings remains ensured.
• An oil-air mixture forms in the riser, which enters the retarder's working area, where it forms an oil film on the inner walls of the working area, which leads to a reduction in power loss and to cooling of the retarder. The heat generated from the power loss is dissipated via the heat exchanger.

Claims (3)

1. Brake installation, particularly for a motor vehicle with a single circuit cooling system;

   1.1 with a hydrodynamic retarder (1 ) which comprises a stator blade wheel (S) and a rotor blade wheel (R) which together form a gap (1.1);

   1.2 with a working medium sump in the main chamber (2.1);

   1.3 with a control device for controlling the filling level of the working chamber of the retarder (1);

   1.4 the control device comprises a proportional valve (3) and connection line (3.1) to the sump;

   1.5 the sump is line connected with the working chamber of the retarder by an ascending channel (2.3);

      characterised by the following features:

   1.6 means are provided to ensure during non-braking operation that the oil level in the main chamber (2.1) and in the ascending channel (2.3) is the same height;

   1.7 the means comprise a line connection between the gap (1.1) of the retarder (1) and the chamber above the sump, wherein said line can be blocked by a valve (1.3);

   1.8 the gap blocking valve (1.3) is connected to the proportional valve (3) by a line (1.5).
2. Brake installation according to claim 1, characterised in that in the line connection between the gap (1.1) of the retarder (1) and the chamber above the sump a restrictor (1.2) is provided in addition to the gap blocking valve (1.3).
3. Brake installation according to one of claims 1 or 2, characterised in that the gap blocking valve comprises a spring (1.5) which holds the gap blocking valve (1.3) open during non-braking operation.

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